1. Field of the Invention
The present invention relates to an automatic ink supply device for a large printer, and more particularly a device utilizing an atmospheric pressure to supply ink for a large printer constantly and automatically, without help of other supplementary equipment, such as a pump or a sensor. In more, the automatic ink supply device of the present invention maintains constant level of ink at a top tank and a bottom tank, while the ink from the external ink source is supplied to the top tank, and while the bottom tank is connected with the top tank. Therefore, it is not necessary to interrupt printing operation of a printer to exchange an ink cartridge.
2. Description of the Related Art
Generally, printing operation of the large printer utilizes piezo method to supply ink to the large printer, while a pump is used to pump a predetermined amount of ink. In this printing method, a sensor is necessary to supply adequate amount of ink to the large printer because a head and an ink cartridge are separated. In more, such printer is complicate, expensive and consumes large amount of ink.
To overcome such problems, Korean Patent No. 20-194011 discloses an automatic ink supply device utilizing an atmospheric pressure to supply ink for a printer continuously. By referring to FIG. 1, a hose 8 having an O/C (open/close) valve 16 connects an ink supply source 2 with an ink cartridge 6 installed in a piezo-jet printer, while the volume of the ink supply source 2 is as big as a few to a few times of that of the ink cartridge 6. In more, by utilizing the height difference H between the ink supply source 2 and the ink cartridge 6, and by utilizing an atmospheric pressure functioning to the ink supply source 2, the level of ink 10 of the ink cartridge 6 is maintained constantly.
In this case, the height difference H between the ink supply source 2 and the ink cartridge 6 is about 35 mm so that the height of the bottom side of a head 12 of the ink cartridge 6 splaying the ink 10 is higher than the height of the ink outlet of the ink supply source 2. Therefore, an adequate amount of ink 22 of the ink supply source 2, as equal as the amount of ink consumed in the ink cartridge 6, is supplied to the ink cartridge 6 automatically through the hose 8.
However, in such a conventional automatic ink supply device, because the volume of the ink supply source 2 is as big as a few to a few times of that of the ink cartridge 6, it is hard to prepare such large space to install the ink supply source 2. In more, after consuming the ink 22 of the ink supply source 2 completely, it is nervous to exchange the empty ink supply source 2 with other full charged ink supply source 2.